July 5, 2020

L’invention concerne une nouvelle cellule Graetzel (ou DSSC: une cellule solaire sensibilisée par un colorant) dotée d’un système de remplissage à la fois de. WOLFBAUER G ET AL: “A channel flow cell system specifically designed to test the efficiency of redox shuttles in dye sensitized solar cells”, SOLAR ENERGY. In , chemist Michael Graetzel of the Swiss Federal Institute of Technology in Lausanne invented so-called dye-sensitized solar cells.

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Solar cells that work in low light could charge devices indoors

Dye-sensitized solar cells already harvest power in buildings around the world. A new discovery could make the hraetzel more celllule.

Imagine never having to charge your phone, e-reader, or tablet again. Researchers report that they have created solar cells that work at a record efficiency for making electricity from the low-intensity diffuse light that is present inside buildings and outside on cloudy days.

The solar cells could one day lead to device covers that continually recharge gadgets without ever having to plug ccellule in. Inchemist Michael Graetzel of the Swiss Federal Institute of Technology in Lausanne invented so-called dye-sensitized solar cells DSSCs that work best in dim light and are cheaper than the standard semiconductors. DSSCs also work a bit differently from standard silicon solar cells.

In standard cells, absorbed sunlight kicks electrons on silicon atoms up to a higher energy level, allowing them to skip across neighboring atoms towards a positively charged electrode.


There they are collected and shunted into an electrical circuit where they can gratezel work. The departed electrons leave behind vacancies in the atoms called holes that, oddly enough, can also move around.

Dye-sensitized solar cell

Over time, the holes travel to the negatively charged electrode where they are filled with electrons from the external circuit. DSSCs take things up a notch.

They still have two electrodes that collect negative and positive charges. But in the middle, instead of just silicon, they have a different electron conductor, typically a collection of titanium dioxide TiO 2 particles.

TiO 2 is a poor light absorber, however. So, researchers coat the particles with organic dye molecules that are exceptional light absorbers. Absorbed photons of light excite electrons and holes on these dye molecules, just as in the silicon. The dyes immediately hand off excited electrons to the TiO 2 particles, which zip them along to the positive electrode. The holes, meanwhile, are dumped into a charge-conducting liquid called an electrolyte, where they percolate through to the negatively charged electrode.

As a result, holes tend to pile up near the dye and TiO 2 particles. If an excited electron ends up bumping into a hole, they celluld, generating heat instead of electricity. But any imperfections in those thin layers can cause the devices to short, a fatal blow that kills the whole solar cell. Now, Graetzel and his colleagues have now come up with a possible solution. They designed a combination of dye and hole-conducting molecules that wrap themselves tightly around TiO 2 particles, creating tight-fitting layers without any imperfections.


That means slow-moving holes have less distance to travel before reaching the negative electrode. The new devices still only convert Until then, diffuse light DSSCs can at least help us power a host of devices without cords, plugs, or external power. Numerous companies are already working to outfit building interiors with an earlier cellulle of DSSCs. And Graetzel says he believes the new and improved cells will only speed up the adoption of the technology.

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